Blockchain, with its decentralization, immutability and transparency, is profoundly transforming multiple fields. However, this technology does not imply absolute security. Issues such as smart contract vulnerabilities, consensus mechanism attacks, and improper private key management can still lead to significant economic losses. How should we ensure the security of the blockchain system during the development process?
I. Main Security Risks Faced by Blockchain Systems
The security of blockchain depends on multiple aspects, including consensus mechanisms, smart contracts, network communication, private key management, data storage, etc. Each link may become a target of attack.
1. Smart contract vulnerabilities
Once a smart contract is deployed on the chain, it cannot be modified. Therefore, code vulnerabilities may lead to the theft of assets or the abuse of functions. Common vulnerabilities in smart contracts include:
Reentrancy attack: Attackers exploit recursive contract calls to repeatedly execute withdrawal logic, such as the TheDAO event.
Integer overflow/Underflow (IntegerOverflow/Underflow) : arithmetic exception, an error calculation, such as Parity multisignature wallet loopholes.
Permission management error: Access control was not set for key functions of the contract, allowing attackers to operate assets at will.
2. Consensus mechanism attack
Different blockchains adopt different consensus mechanisms (such as PoW, PoS, DPoS, etc.), but the consensus algorithms themselves also carry attack risks:
51% attack: The attacker controls more than 50% of the computing power or rights, allowing for the reorganization of blocks and double-spending transactions. For instance, Ethereum Classic (ETC) has suffered a 51% attack.
Selfish mining: Miners conceal block information in pursuit of higher mining returns, which affects the security of the entire network.
Fork attack: Malicious nodes deliberately create chain forks to interfere with the transaction confirmation process.
3. Transaction security risks
Blockchain transactions are usually irreversible. If the transaction signature or broadcasting process is hijacked, it may lead to the theft of assets.
Man-in-the-middle attack (MITM) : The attacker intercepts transaction requests, tampers with the receiving address, and uses the user's assets to flow into the hacker's account.
ReplayAttack: In cross-chain operations or forked chains, attackers repeatedly send the same transaction, resulting in unexpected fund transfers.
Transaction sorting attack (Front-running) : In DeFi transactions, miners or MEV (Maximum Extractable Value) robots can predict transactions and place orders in advance to make profits.
4. Private key and key Management risks
The ownership of a blockchain is controlled by a private key. Once leaked, the assets cannot be recovered.
Improper storage of private keys: Developers hard-code private keys in smart contracts or public repositories on GitHub, resulting in key leakage.
Mnemonic phrase phishing attack: Hackers use social engineering to induce users to disclose mnemonic phrases and steal wallet funds.
Multi-signature failure: Without an appropriate recovery mechanism, the loss of part of the private key may lead to the permanent freezing of assets.
Ii. Emergency Response Strategies: How to Respond Quickly to Security Threats?
Even if strict security measures are taken, a timely and effective emergency response is the key to reducing losses once an attack occurs. The following is the standard emergency response procedure for blockchain system security incidents:
Event monitoring and early warning
Build a real-time monitoring system: Use on-chain monitoring tools (such as Chainalysis, Forta) to detect abnormal transactions and contract calls in real time.
Set up multi-layer alerts: For large transactions, batch withdrawals, abnormal Gas fees and other situations, set up automated alerts.
Smart contract visualization analysis: Code behavior tracking using Etherscan and SolanaExplorer.
2. Quickly freeze suspicious transactions
Multi-signature mechanism: In multi-signature wallets (such as GnosisSafe), administrators can urgently freeze assets to prevent capital outflows.
Centralized exchange (CEX) cooperation: If assets flow into the exchange, the attacker's account can be quickly frozen.
On-chain governance mechanism: For DAO organizations, they can vote to suspend smart contracts to prevent further attacks.
3. Conduct event traceability analysis
Audit transaction records: Use TheGraph and DuneAnalytics to analyze the sources of malicious transactions.
Reverse analysis of smart contracts: Use Slither and Mythril tools to mine vulnerabilities in contract code.
Tracking hacker wallets: Monitor the flow of hacker funds through Etherscan and ArkhamIntelligence.
4. Develop remedial and repair plans
Rollback or compensation mechanism: If the consensus mechanism permits, hard fork rollback transactions can be carried out (such as the Ethereum TheDAO incident).
Vulnerability repair and upgrade: For upgradable contracts, emergency fixes are carried out using the ProxyPattern.
Legal affairs and tracking: Report hackers to judicial authorities and cooperate with law enforcement departments to recover funds.
Iii. Prevention and Mitigation Strategies: How to Maximize the Reduction of Security Risks?
1. Practice of Smart Contract Security Development
When using a security framework: It is recommended to use OpenZeppelin for permission management during Solidity development.
Strict permission control: Use Ownable and AccessControl to set the key functional permissions of the contract.
Code audit: Before deployment, conduct third-party audits (such as CertiK, TrailofBits) to identify potential vulnerabilities.
2. Enhance the anti-attack capability of the consensus mechanism
Introduce a Checkpointing mechanism to reduce the risk of 51% attacks.
Optimize the PoS staking requirements and increase the cost for malicious nodes to act maliciously.
Implement Timelock to prevent governance attacks from affecting contract upgrades.
3. Transaction and key security management
Use hardware wallets (Ledger, Trezor) to avoid exposing private keys.
Enhance the security of private keys by using MPC (Multi-Party Computation) or ThresholdSignature.
The transaction whitelist mechanism only allows authorized addresses to perform critical operations.
4. Business logic Security Policy
Prevent fake recharges: Update the user's balance only after the transaction is confirmed to avoid fraud attacks.
Anti-mev transactions: Use Flashbots to protect transactions from pre-attack attacks.
Set up a revocation mechanism: Add a "revocation period" to the contract function to prevent malicious operations from taking effect immediately.
Conclusion
The decentralized nature of blockchain technology makes it difficult to recover losses through traditional means once security issues occur. Therefore, from the identification of security risks, emergency response to long-term prevention, every link needs to be strictly controlled.
"Safety is not achieved overnight but is a continuous process of optimization." " In blockchain development, only by constantly strengthening security strategies can an efficient, secure and sustainable blockchain system be built.
